I have found it easier to photograph my models with just a monotone background and then splicing in another photo background using my photo editting software. For many years, I have tried to photograph my dioramas with large poster-sized backdrops, but I have had several problems. The first problem is depth of field. Most of the time, unless you are using a very wide-angle lens, you can not get all of the model in focus, even at f22 or f32. The background will be all of a indistinct, fuzzy blob. The next problem is shadows falling on the backdrop. If you have large, tall objects in the diorama, like buildings, trees, etc., their shadows will fall upon the background, which doesn't look very good. This will then require that you move the background further away, thus compounding the depth of field problem. It is much easier to photograph the model standing alone, selecting and deleting the background, then cut and paste the model photo into your desired background image.